Yes, the berm is for watering a recently planted tree.

No to the compacting the berm.

What are you hoping to accomplish by reducing berm? I guess that's what you mean by compacting? I think you could apply a thin layer of mulch inside the berm for weed control, with care that no mulch touches the trunk, IOW no mulch volcanoes.

Your mini-berm keeps the water from running away from the tree so that the plant gets enough water while it is getting established. I'd leave it for the first growing season, but you can also add a light layer of mulch both inside and outside the berm if you want to keep down weeds and add a neater appearance; just be sure that the mulch is several inches from the trunk to prevent rotting.

in 2 to 3 years.. of proper watering ... the tree should be free range... and at that point ... you can stop watering... and remove the moat, as i prefer to call it ...

you can fill the moat with some mulch .. but keep it off the trunk itself ...

see link for watering protocol ..

ken

https://sites.google.com/site/tnarboretum/Home/planting-a-tree-or-shrub

Remove the berm as soon as the tree has established itself in your yard, usually about a year after planting.

Don't wait too much longer as the roots will grow into the berm and when the berm is removed will be sticking out of the ground.

This is what happened to a Nuttal Oak that I planted when we bought our current house. I tried to bury them, but they are still popping out of the ground.

It looks as if you want to remove the berm and plant a lawn right up to the tree. In most cases that's a mistake because the lawn mower will either hit the tree or not be able to mow all the way up to the tree. Then the string trimmer gets it's chance to strip the bark off the trunk.

Shame on the landscapers for doing a sloppy job on that berm.

Mike

Like Ken, I don't usually call what we're talking about here a berm (although technically, I guess one could think of it as a circular-shaped water-retaining berm). Typically, these features gradually disappear on their own within a year or less. The ones that I make are always gone or mostly gone within one year. The one in the picture is needlessly large and could be flattened out a little, immediately, without any problem for the establishment of the tree.